The Strip’s largest resort construction project hit a major milestone Friday morning as the final structural beam was placed atop the Guitar Hotel Las Vegas. Nineteen months to the day that ground first broke at the site of the former Mirage hotel-casino, Hard Rock International and Seminole Gaming hosted a topping-off ceremony to commemorate structural completion of the 660-foot guitar-shaped hotel at the center of the Strip. “We sit here at the foot of a structure that will change the skyline, will bring in millions more visitors to the Las Vegas Strip, and also employ up to 6,000 Las Vegas residents from our community,” said Joe Lupo, president of Hard Rock Las Vegas.…